Yes, I've had this happen to me on multiple occasions by my teacher, my co worker and a roomate. Yes, I am a guy.
I guess it's a compliment??? But it's also somewhat creepy...
I kinda have mixed feelings about these kinds of things...

Speaking as an old guy myself, I think it depends on context.
I mean, if you're at a party and some old geezer comes over to you, leering, and declares that he finds you 'pretty', I could certainly see how that could be construed as creepy.
If it's just in passing, as part of a broader conversation - "Hey, you're a pretty guy, you're probably a good person to ask about this..." or whatnot, then It's more likely an innocent comment.
Personally, I avoid this problem by only associating with ugly people. Life is so much easier that way.

Yeah men used to hit on me all the time when I was younger, so I grew a beard hoping it would stop. Well that's not the only reason I grew a beard...

I don't particularly find it creepy, though if it just came up in random conversation with somebody I guess it would be a bit, I mean I think it would be weirder if my friends said it than a total stranger.

I have had women call me pretty, but never a guy....so I don't know what that is
There were older guys who would say your a handsome guy or a good looking young man,
but by the way they said it-it was obviously more of just a bro-compliment.

Yes, I've had this happen to me on multiple occasions by my teacher, my co worker and a roomate. Yes, I am a guy.
I guess it's a compliment??? But it's also somewhat creepy...
I kinda have mixed feelings about these kinds of things...

They call that an "Easy A".

Seriously though I'd say it depends on context. If they are just saying "pretty" and not insinuating anything else then it is most likely innocent. However, if there are larger insinuations then that is a bit creepy.